1. Field of the Invention
The invention relates generally to packages and more specifically to packages and packaging methods in which a product supported in a tray is wrapped with a film which is selectively affixed to the tray using a heat activated adhesive.
2. Description of the Prior Art
In a typical prior art package and packaging technique the product is placed in a tray and covered with a plastic film such that the film totally encloses the tray and the product. Heat is applied to the bottom of the package. Portions of the film which overlap such that contact is established therebetween adhere to form a seal.
Such packaging techniques are widely used in the food industry to package food products which include moisture. Since the plastic film adheres to itself, a relatively leak-proof seal is formed in areas where the film overlaps without wrinkles or excessive overlaping layers. Wrinkles and excessive overlaping layers adversely effect the sealing characteristics of the film resulting in an increase in the number of packages which develop leaks.
Areas forming a good seal are usually concentrated in the central portion of the package. Areas near or adjacent the ends usually include excessive overlaping layers and wrinkles. Wrinkles and excessive overlaping layers change the sealing characteristics as a result of the formation of regions where no contact is established between overlaping layers of the film. Passages are formed along the wrinkles and between excessive overlaping layers which may extend from the interior of the package to the exterior of the package.
The inside surface of the film is typically treated to prevent the formation of water droplets. Condensation forming on the inside surface of the film tends to flow along this surface and through the passageways, discussed above. As a result, the package leaks and must be removed from the shelf before it is sold. Such leaks are particularly troublesome when food products such as fresh meats, poultry and seafood are to be packaged due to the high moisture content of these products.